TENTH AMENDMENT TO AMENDED AND RESTATED LIMITED PARTNERSHIP AGREEMENT

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Exhibit 10.1.9

TENTH
AMENDMENT
TO
AMENDED AND RESTATED
LIMITED PARTNERSHIP AGREEMENT
OF
THE MACERICH PARTNERSHIP, L.P.

Dated as of October 26, 2006

        THIS TENTH AMENDMENT (the " Amendment ") TO THE AMENDED AND RESTATED LIMITED PARTNERSHIP AGREEMENT DATED AS OF MARCH 16, 1994, AMENDED AS OF AUGUST 14, 1995, FURTHER AMENDED AS OF JUNE 27, 1997, FURTHER AMENDED AS OF NOVEMBER 16, 1997, FURTHER AMENDED AS OF FEBRUARY 25, 1998, FURTHER AMENDED AS OF FEBRUARY 26, 1998, FURTHER AMENDED AS OF JUNE 17, 1998, FURTHER AMENDED AS OF DECEMBER 23, 1998, FURTHER AMENDED AS OF NOVEMBER 9, 2000, AND FURTHER AMENDED AS OF JULY 26, 2002 (the " Agreement ") OF THE MACERICH PARTNERSHIP, L.P. (the " Partnership "), dated as of October 26, 2006, is hereby adopted by The Macerich Company, a Maryland corporation (the " Company "), as the general partner of The Macerich Partnership, L.P., a Delaware limited partnership. For ease of reference, capitalized terms used herein and not otherwise defined have the meanings assigned to them in the Agreement.

        WHEREAS, the General Partner desires to establish and set forth the terms of a new class of Partnership Interests designated as LTIP Units;

        WHEREAS, the LTIP Units shall have the terms set forth in Exhibit B to this Amendment;

        WHEREAS, Section 3.3(a)(i) of the Agreement authorizes the General Partner to cause the Partnership to issue additional interests in the Partnership in one or more classes, or one or more series of any of such classes, with such designations, preferences and relative, participating, optional or other special rights, powers and duties, including rights, powers and duties senior to those of the Limited Partners, all as shall be determined by the General Partner in its sole and absolute discretion and without the approval of any of the Limited Partners;

        WHEREAS, Section 12.1(b)(iii) of the Agreement provides that the General Partner has the power, without the consent of the Limited Partners of the Partnership, to amend the Agreement as may be required to facilitate or implement setting forth the designations, rights, powers, duties, and preferences of the holders of any additional interests in the Partnership issued pursuant to Section 3.3; and

        WHEREAS, the General Partner has made the determination pursuant to Section 12.1(b)(iii) of the Agreement that consent of the Limited Partners of the Partnership is not required with respect to the matters set forth in this Amendment.

        NOW, THEREFORE, the General Partner hereby amends the Agreement as follows:

        1.     Section 2.2 of the Agreement is hereby supplemented by adding the following paragraphs (f), (g) and (h) to the end thereof:

        (f)     Reserved.

        (g)    Reserved.

        (h)    Issuance of LTIP Units . From and after the date hereof the Partnership shall be authorized to issue LTIP Units. From time to time the General Partner may issue LTIP Units to Persons providing services to or for the benefit of the Partnership. LTIP Units are intended to

qualify as profits interests in the Partnership. LTIP Units shall have the terms set forth in Exhibit B to the Tenth Amendment to this Agreement.

        2.     New Section 4.1A of the Agreement is hereby added to read as follows:

        For purposes of the foregoing calculations of Section 4.1, issued and outstanding LTIP Units with an associated LTIP Unit Distribution Participation Date that falls on or before the Partnership Record Date for a particular distribution shall be treated as outstanding Common Units. LTIP Units for which the LTIP Unit Distribution Participation Date has not occurred as of the Partnership Record Date for a particular distribution shall not be entitled to any of such distribution.

        3.     In making distributions pursuant to Section 4.1 of the Agreement and allocations pursuant to Sections 2.1 and 2.2 of the Allocations Exhibit, the General Partner of the Partnership shall take into account the provisions of Exhibit B to the Tenth Amendment to this Agreement.

        4.     Section 5.5 of the Partnership Agreement is amended by designating the existing text of Section 5.5 as Section 5.5(a), and by appending the following new Section 5.5(b):

        (b)   To the extent provided for in Regulations, revenue rulings, revenue procedures and/or other IRS guidance issued after the date hereof, the Partnership is hereby authorized to, and at the direction of the General Partner shall, elect a safe harbor under which the fair market value of any Partnership Interests issued after the effective date of such Regulations (or other guidance) will be treated as equal to the liquidation value of such Partnership Interests (i.e., a value equal to the total amount that would be distributed with respect to such interests if the Partnership sold all of its assets for their fair market value immediately after the issuance of such Partnership Interests, satisfied its liabilities (excluding any non-recourse liabilities to the extent the balance of such liabilities exceed the fair market value of the assets that secure them) and distributed the net proceeds to the Partners under the terms of this Agreement). In the event that the Partnership makes a safe harbor election as described in the preceding sentence, each Partner hereby agrees to comply with all safe harbor requirements with respect to transfers of such Partnership Interests while the safe harbor election remains effective.

        5.     Article IX of the Agreement is hereby supplemented by adding the following paragraphs (f), (g), (h) and (i) at the end of Section 9.1 thereof:

        (f)    Reserved.

        (g)   Reserved.

        (h)   Reserved.

        (i)    Holders of LTIP Units shall not be entitled to the Redemption Rights provided for in Section 9.1 of this Agreement, unless and until such LTIP Units have been converted into Common Units (or any other class or series of Partnership Units entitled to such Redemption Rights). Notwithstanding the foregoing, and except as otherwise permitted by the award, plan or other agreement pursuant to which an LTIP Unit was issued, the Redemption Rights shall not be exercisable with respect to any Common Unit issued upon conversion of an LTIP Unit until two years after the date on which the LTIP Unit was issued, provided however, that the foregoing restriction shall not apply if the right of Redemption is exercised by an LTIP Unit holder in connection with a transaction that falls within the definition of a "change of control" under the agreement or agreements pursuant to which the LTIP Units were issued to such holder.

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        6.     The following definitions contained in the Glossary of Defined Terms of the Agreement are amended as follows:

        (a)   The definition of the term "Common Unit" contained in the Glossary of Defined Terms of the Agreement is hereby amended and restated in its entirety as follows:

"Common Unit" shall mean Partnership Interests other than Preferred Units, Series A Preferred Units, Series B Preferred Units, Series D Preferred Units, Series N Preferred Units, Series P Preferred Units and LTIP Units.

        (b)   The definition of the term "Partnership Interest" contained in the Glossary of Defined Terms of the Agreement is hereby amended and restated in its entirety as follows:

"Partnership Interest" shall mean an ownership interest of a Partner in the Partnership from time to time, including, as applicable, such Partner's Common Units, Preferred Units, Series A Preferred Units, Series B Preferred Units, Series D Preferred Units, Series N Preferred Units, Series P Preferred Units, LTIP Units and Percentage Interest and such Partner's Capital Account, and any and all other benefits to which the holder of such Partnership Interest may be entitled as provided in this Agreement, together with all obligations of such Person to comply with the terms of this Agreement.

        (c)   The definition of the term "Partnership Unit" contained in the Glossary of Defined Terms of the Agreement is hereby amended and restated in its entirety as follows:

"Partnership Unit" shall mean a Common Unit, Preferred Unit, Series A Preferred Unit, Series B Preferred Unit, Series D Preferred Unit, Series N Preferred Unit, Series P Preferred Unit or LTIP Unit and shall constitute a fractional, undivided share of the Partnership Interests corresponding to that particular class of Units.

        (d)   The definition of the term "Percentage Interest" contained in the Glossary of Defined Terms of the Agreement is hereby amended and restated in its entirety as follows:

"Percentage Interest" shall mean, with respect to any Partner, the percentage ownership interest of such Partner in the Partnership from time to time, represented by a fraction (expressed as a percentage), the numerator of which is the number of Partnership Units then owned by such Partner, and the denominator of which is the total number of Partnership Units then owned by all of the Partners. For purposes of calculations of Percentage Interests at any time, the Percentage Interest of any LTIP Unit Limited Partner and the total number of Partnership Units shall exclude any LTIP Units for which the LTIP Unit Distribution Participation Date has not occurred as of such time.

        7.     The Glossary of Defined Terms of the Agreement is amended by inserting the following definitions in alphabetical order:

" 2006 LTIP Plan " has the meaning set forth in Section 3.B of Exhibit B to the Tenth Amendment to this Agreement.

" Book-Up Target " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" Common Unit Economic Balance " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" Constituent Person " has the meaning set forth in Section 7.G of Exhibit B to the Tenth Amendment to this Agreement.

" Economic Capital Account Balance " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

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" Ineligible Unit " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" Liquidating Gains " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" Liquidating Losses " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" LTIP Unit Adjustment Events " has the meaning set forth in Section 5 of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Conversion Date " has the meaning set forth in Section 7.C of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Conversion Notice " has the meaning set forth in Section 7.C of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Conversion Right " has the meaning set forth in Section 7.A of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Distribution Participation Date " has the meaning set forth in Section 3.B of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Distribution Payment Date " has the meaning set forth in Section 3.A of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Forced Conversion " has the meaning set forth in Section 7.D of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Forced Conversion Notice " has the meaning set forth in Section 7.D of Exhibit B to the Tenth Amendment to this Agreement.

" LTIP Unit Limited Partner " means any Person holding LTIP Units, and named as a LTIP Unit Limited Partner in Exhibit A attached hereto, as such Exhibit or the Partnership's records may be amended from time to time.

" LTIP Units " means the Partnership Units designated as such having the rights, powers, privileges, restrictions, qualifications and limitations set forth in Exhibit B to the Tenth Amendment to this Agreement.

" Partnership Record Date " means the record date established by the General Partner for the distribution of cash pursuant to Section 4.1 hereof, which record date shall be the same as the record date established by the General Partner for the payment of dividends to holders of Common Stock of the General Partner on account of some or all of the General Partner's share of such distribution by the Partnership.

" Series N Preferred Units " shall mean Partnership Units so designated by the General Partner and reserved for future issuance in connection with the partnership units of MACWH, L.P.

" Series P Preferred Units " shall mean Partnership Units so designated by the General Partner and reserved for future issuance in connection with the partnership units of MACWH, L.P.

" Target Balance " has the meaning set forth in Section 3.10 of the Allocations Exhibit.

" Transaction " has the meaning set forth in Section 7.G of Exhibit B to the Tenth Amendment to this Agreement.

" Unvested LTIP Units " has the meaning set forth in Section 2.A of Exhibit B to the Tenth Amendment to this Agreement.

" Vested LTIP Units " has the meaning set forth in Section 2.A of Exhibit B to the Tenth Amendment to this Agreement.

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" Vesting Agreement " has the meaning set forth in Section 2.A of Exhibit B to the Tenth Amendment to this Agreement.

        8.     The term "Profit or Losses" contained in the Allocations Exhibit is hereby amended to read "Net Income or Net Losses" in each place it is located.

        9.     Section 1.3(b) of the Allocations Exhibit is hereby amended and restated in its entirety as follows:

        (b)   Immediately prior to the times listed below, the Gross Asset Values of all Partnership assets shall be adjusted to equal their respective gross fair market values, as determined by the General Partner using such reasonable method of valuation as it may adopt:

          (i)  the acquisition of an additional interest in the Partnership by any new or existing Partner in exchange for more than a de minimis Capital Contribution;

         (ii)  the acquisition of a more than de minimis additional interest in the Partnership by any new or existing Partner as consideration for the provision of services to or for the benefit of the Partnership in a partner capacity or in anticipation of becoming a partner; provided, however, at the time of grant of any LTIP Unit, the Gross Asset Values of all Partnership assets shall be adjusted pursuant to this Section 1.3(b);

        (iii)  the distribution by the Partnership to a Partner of more than a de minimis amount of property as consideration for an interest in the Partnership; and

        (iv)  the liquidation of the Partnership within the meaning of Regulations Section 1.704-1(b)(2)(ii)(g);

provided however that adjustments pursuant to clauses (i), (ii) and (iii) above shall be made only if the General Partner determines that such adjustments are necessary or appropriate to reflect the relative economic interests of the Partners in the Partnership.

        10.   Section 2.1A is added to the Allocations Exhibit as follows:

        For purposes of determining allocations of Net Income pursuant to Section 2.1, to the extent that the LTIP Unit Distribution Participation Date with respect to an LTIP Unit has occurred, such LTIP Unit shall be treated as a Common Unit.

        11.   Section 2.2A is added to the Allocations Exhibit as follows:

        For purposes of determining allocations of Net Loss pursuant to Section 2.2, to the extent that the LTIP Unit Distribution Participation Date with respect to an LTIP Unit has occurred, such LTIP Unit shall be treated as a Common Unit.

        12.   Section 3 of the Allocations Exhibit is hereby supplemented by appending the following new Section 3.9:

        3.9    Forfeiture Allocations . Upon a forfeiture of any unvested Partnership Interest by any Partner, gross items of income, gain, loss or deduction shall be allocated to such Partner if and to the extent required by final Regulations promulgated after the effective date of the Tenth Amendment to this Agreement to ensure that allocations made with respect to all unvested Partnership Interests are recognized under Code Section 704(b).

        13.   Section 3 of the Allocations Exhibit is hereby supplemented by adding the following new Sections 3.10 and 3.11 to the end thereof:

        3.10    Special Allocations With Respect to LTIP Units.

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        (a)   After giving effect to the special allocations set forth in Sections 3.1 through 3.9 hereof, and the allocations of Net Income (including, for the avoidance of doubt, Liquidating Gains that are a component of Net Income) under Subsections 2.1(a) through (e) above, but before allocations of Net Income are made under Section 2.1(f) above, any remaining Liquidating Gains shall first be allocated to the holders of LTIP Units until the Economic Capital Account Balances of such holders, to the extent attributable to their ownership of LTIP Units, are equal to (i) the Common Unit Economic Balance, multiplied by (ii) the number of their LTIP Units (with respect to each holder, the " Target Balance "); provided , however , that no such Liquidating Gains will be allocated with respect to any particular LTIP Unit (each, an " Ineligible Unit ") if cumulative Liquidating Losses of the Partnership have exceeded cumulative Liquidating Gains of the Partnership during the period from the issuance of such LTIP Unit through the date of such allocation. If, notwithstanding the foregoing, not all LTIP Units (including Ineligible Units) are fully booked up, Liquidating Gains shall be allocated among LTIP Units in a manner reasonably determined by the General Partner. For the avoidance of doubt, Liquidating Gains allocated with respect to an LTIP Unit pursuant to this Section 3.10(a) shall reduce (but not below zero) the Book-Up Target for such LTIP Unit.

        (b)   After giving effect to the special allocations set forth in Sections 3.1 through 3.9 hereof, and notwithstanding the provisions of Sections 2.1 and 2.2 above, if, due to distributions with respect to Common Units in which the LTIP Units do not participate, forfeitures or otherwise, the Economic Capital Account Balance of any present or former holder of LTIP Units, to the extent attributable to the holder's ownership of LTIP Units, exceeds the Target Balance, then Liquidating Losses shall be allocated to such holder to eliminate the disparity; provided, however, that if Liquidating Losses are insufficient to completely eliminate all such disparities, such losses shall be allocated among LTIP Units in a manner reasonably determined by the General Partner.

        (c)   A " Book-Up Target " shall be established for each LTIP Unit. The initial amount of the Book-Up Target for such LTIP Unit shall be the Common Unit Economic Balance as determined on the later of (i) the date such LTIP Unit was granted or (ii) the LTIP Unit Distribution Participation Date. The Book-Up Target shall be reduced (not to less than zero) by allocations of Liquidating Gains pursuant to Section 3.10(a) and reallocations of Capital Account balances pursuant to Section 3.11, as determined by the General Partner. Notwithstanding the foregoing, the Book-Up Target for any LTIP Unit for which the Economic Capital Account Balance attributable to such LTIP Unit has at any time reached an amount equal to the Common Unit Economic Balance determined as of such time shall be equal to zero.

        (d)   The parties agree that the intent of this Section 3.10 is, (i) to the extent possible, to make the Capital Account balance associated with each LTIP Unit economically equivalent to the Capital Account balance associated with the General Partner's Common Units (on a per-unit basis), and (ii) to allow conversion of an LTIP Unit (assuming prior vesting) when sufficient Liquidating Gains have been allocated to such LTIP Unit pursuant to Section 3.10(a) so that either its initial Book-Up Target has been reduced to zero or the parity described in (i) above has been achieved. The General Partner shall be permitted to interpret this Section 3.10 or to amend this Agreement to the extent necessary and consistent with this intention.

        (e)   For purposes of this Allocations Exhibit, the following definitions shall apply:

        " Liquidating Gains " means any net gain realized in connection with the actual or hypothetical sale of all or substantially all of the assets of the Partnership (including upon the occurrence of any event of liquidation of the Partnership), including but not limited to net gain realized in

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connection with an adjustment to the Gross Asset Value of Partnership assets under the definition of Gross Asset Value in Section 1.3 of the Allocations Exhibit.

        " Liquidating Losses " means any net loss realized in connection with the actual or hypothetical sale of all or substantially all of the assets of the Partnership (including upon the occurrence of any event of liquidation of the Partnership), including but not limited to net loss realized in connection with an adjustment to the Gross Asset Value of Partnership assets under the definition of Gross Asset Value in Section 1.3 of the Allocations Exhibit.

        " Economic Capital Account Balance " means, with respect to a holder of LTIP Units, as of any date, its Capital Account balance, plus the amount of its shares of any Minimum Gain Attributable to Partner Nonrecourse Debt or Partnership Minimum Gain, in either case as of such date and only to the extent attributable to its ownership of LTIP Units.

        " Common Unit Economic Balance " shall mean as of any date, (i) the Capital Account balance of the General Partner, plus the amount of the General Partner's share of any Minimum Gain Attributable to Partner Nonrecourse Debt or Partnership Minimum Gain, in either case to the extent attributable to the General Partner's ownership of Common Units and computed on a hypothetical basis after taking into account all allocations through such date divided by (ii) the number of the General Partner's Common Units as of such date. !

        3.11    Special Forfeiture Reallocations . If, in connection with any forfeiture of LTIP Units, the balance of the portion of the Capital Acc